Linux File System Navigation

Chapter 2: File and Directory Management

• Chapter 2 concerns file and directory management in Operating Systems 2, specifically TECM 113.
• The chapter outline includes an introduction, Linux directory structure, management of directories and files, removable storage, and a conclusion.

Objectives

• The chapter aims to facilitate understanding and navigation of the Linux directory structure using relative and absolute pathnames.
• Further objectives include the utilization of standard Linux commands for file and directory management, the description of various Linux file types, displaying contents of text and binary files, and searching text files for regular expressions using grep.
• Use the vi editor is a further objective, to manipulate text files.

Linux Directory Structure

• A directory is used to organize files into a logical tree structure.
• An absolute pathname is a pathname from the root directory (/) to a specific file or directory.
• Root is the top-level directory, referred to using the / character, and forms the root of a hierarchical tree.
• The following is an example directory structure:
  • /: "root"
  • /bin: essential binaries
  • /boot: static files of the bootloader
  • /dev: device files
  • /etc: host-specific system config
  • /home: user home directories
  • /lib: library and kernel modules
  • /mnt: mount files for temporary filesystems.
  • /opt: add-on application software
  • /root: "home dir for root user

Linux Directories Defined

• /bin: contains binary commands for use by all users.
• /boot: contains the Linux kernel and files used by the boot loader.
• /dev: contains device files.
• /etc: contains system-specific configuration files.
• /home: default location for user home directories.
• /lib: contains shared program libraries which are used by the commands in /bin and /sbin, as well as kernel modules.
• /mnt: is the empty directory used for accessing (mounting) disks, such as floppy disks and CD-ROMs.
• /opt: stores additional software programs.
• /proc: contains process and kernel information.
• /root: is the root user's home directory.
• /sbin: contains system binary commands, used for administration.
• /tmp: holds temporary files created by programs.

Changing Directories

• Home directory is unique to each user.
• pwd (print working directory) command displays current directory in the directory tree.
• cd (change directory) command changes the current directory in the directory tree.
• An argument specifies the destination directory for the change directory command.
• ~ metacharacter refers to the home directory (personal directory).
• A relative pathname is the pathname of a file or directory relative to the current directory.
• Parent directory is one step closer to the root of the tree.
• $cd .. command moves to the parent directory.
• A subdirectory is a directory residing within another directory.
• Tab-completion involves pressing the tab key to fill in the remaining characters of a unique file name or directory name.

Viewing Files and Directories: File Types

• Text files store information in a readable text format and contain configuration information.
• Binary data files store information associated with executable programs.
• Executable program files are executable.
• Directory files serve as place holders to organize other files.
• Linked files associate with another file.
• Special device files represent system devices.
• Named pipes identify the channel that passes information between processes.
• Socket files allow a process on another computer to write to a local file.

File Names

• A file name is an identifier given to a file.
• File name extensions are identifiers that follow a dot (.) at the end of a file name. Most files on Linux do not have file extensions.

Common File Name Extensions

• .c is a C programming language source code file.
• .cc is a C++ programming language source code file.
• .cpp is a C++ programming language source code file.
• .html Hypertext Markup Language
• .htm Hypertext Markup Language
• .ps file formatted for printing with postscript
• .txt is a text file.
• .tar is an archived files (contain other files within).
• .gz is a compressd file.
• .bz2 is a compressd file.
• .Zis a compressd file.
• .tar.gz is compressed archived files.
• .tgz is compressed archived files.
• .tar.bz2 is compressed archived files.
• .tar.Z is compressed archived files.
• .conf is a configuration files(contain text).
• .cfg is a configuration files(contain text).
• .so is a shared object (programming library) files.
• .o is a compiled object files.
• .pl is a PERL (Practical Extraction and Report Language) program.
• .tcl is a Tcl (Tool Command Language) program.
• .jpg is a Binary files that contain graphical images format.
• .jpeg is a Binary files that contain graphical images format.
• .png is a Binary files that contain graphical images format.
• .tiff Binary files that contain graphical images format.
• .sh is shell script file(contain text that is executed by the shell .xpm is a Binary files that contain graphical images format. .gif is a Binary files that contain graphical images format.

Directory Management

• mkdir command creates new directories.
• -p option used with mkdir creates more than one directory.
• The mv command is to move files.
• mv command requires two arguments minimum - a source and a destination.
• The first argument for mv is the source file/directory.
• The second argument for mv is the target file/directory.
• mv is also used to rename files.
• The cp command is to copy files.
• cp command requires two arguments minimum - a source and a destination. The first argument for cp command is the source file/directory.
• The second argument for cp command is the target file/directory.
• Use -r to copy the folder and its content when the folder is not empty.
• The rm command removes files or directories
• The "rmdir command removes empty directoies.
• The -r is used to remove a directory and its content with the rm command.

Common Linux file management tools

• mkdir creates directories.
• rmdir removes empty directories.
• mv moves/renames files and directories.
• cp copies files and directories, including all the files inside directories (with the -r option).
• alias displays BASH shell aliases.
• rm removes files and directories, including all the files inside directories (with the -r option).

File Management - Listing Files

• The ls command lists the files in a directory.
• The lscommand can be passed an argument indicating the directory to be Listed. -F argument with ls lists file types.
• -l argument with ls lists long file listings (listing with details).
• file command: displays file-type
• Hidden files are not normally displayed to users.
• File names start with a dot (.).
• Configuration files are often hidden.
• $ls -a displays all files, including hidden files.

Common Options to the Is Command

• -a lists all files, including hidden files.
• -A lists all files, excluding the special entries "." and "..".
• -C lists files in column format.
• -f lists all the files without sorting.
• -F classifies files by type, adding "/"" after each directory, "*" after a file, and "@" after a link.
• -r lists files in reverse sorted order.
• -R lists the files in the specified directory and all subdirectories.
• -s lists the files and their associate size in KiloBytes.
• -S lists The files sorted by filesize
• -t Lists the files sorted by modification time

File Management - Creating Files and Aliases

• Alias: shortcut for a command
• Example: $alias C= "clear" will run clear every time Cis entered
• $alias command lists the existent alias
• touch command to create an empty file.
• Example: touch /home/Lina/OS will create a file named OS

File Management - Displaying Content of Text Files

• less is a command to display a file.
• more is a command to display a file.
• cat is a command to display a file.
• Example 1: $cat /etc/passwd displays the content of the file passwd.
• Example 2: $less /etc/passwd displays the content of the file passwd.
• Concatenation joins text together.
• cat command: the cat command is used to display (concatenates) contents of a text file to the screen.
• -n option to display the line number and cotents
• head command to view first 10 lines of a file head /us/share/dict/words will display the first 10 lines of the word file
• To limit the numbers of line using the head command, use the -n option followed by the number of lines to show head -n 1 /usr/share/dict/words Will display the first line of the word document.
• tail file to view last 10 lines of a file tail -n 3 state.txt views only the last 3 lines

Tac Command

• Tac displays display files in reverse order
• Example
  • content of text file
    • A
    • B
    • C
    • D
  • running $cat file1 results in
    • A
    • B
    • C
    • D
  • running $tac file1 results in
  • D
  • C
  • B
  • A

Grep Command

• Finds string of characters specified, in a specified file
• grep is the acronym of Global Regular Expression Print
• Displays lines in a text file matching a given string
• Requires following two arguments grep: text to search for and files to search
• the syntax $grep stirngToMatch file runs the comand to fine *stirngToMatch from file
• example $ grep phoenixNAP sample finds phoenixNAP from sample

Editing Files

• Vi
• Vi is one of the oldest and most popular test editor of UNIX OS
• Vi Editor which works the same across diffferent Platforms and distributions
• Syntax: vi filenam_new or vi filename_existing

vi is the command used in CLI to edit text files

• In Vi to write in a file ,press i shift =zz to save and close the file :w'' to save the file but keep it open "":q!'' To quit wo saving "wq``" To save the file and quit"

Common vi Functions

• Description Changes to insert mode and places the cursor before the current character for entering text
• Key i
• Changes to insert mode and places the cursor after the current character for entering text a
• Changes to insert mode and opens a new line underneath the current line for entering text 0
• Changes to insert mode and places the cursor at the beginning of the current line for entering text l
• Changes to insert mode and places the cursor at the end of the current line for entering text A
• Changes to insert mode and opens a new line above the current line for entering text 0
• Changes back to command mode while in insert mode Esc- Vim

Vim Editor

• VimEditor
• Vim ( is Improved)
• Vim :Linux- equivalent of Vi(it is Vi Improved)
• Syntax vim: syntax Vim<filename_new>````$vim`Text1 ""To write in a file the press" ::1 Shift"+zz``to save and close the file ::2"w" To Save The Fire But keep it Open` "":: To quite without saving ``:4 WQ "" To Save the Five and quite,`,

Editors

• Mcedit: Midnight Commander . easier to use with highlighting and mouse support

Emacs Editor

• emacs editor offers comparable functionality to vi and supports list processing
• It has the following functions
  • ctrl+ amoves cursor to beginning of line
  • ctrl +e moves cursor to the end of the line -ctrl +h displays emac documentation -ctrl d Deletes current chatacter -ctrl +k .deleter from curdso position to end of line -csc d deletes current word -ctrl x + ctrl +cexits emal editor ctrlx + ctrl s``" saves current document ctrl + ctrl w. Saves the document `ctrl x +4` udcoes last change
• Xemacs: is the versiion oh Emacs for KDE GNome qu environments
• "easier too use" not availble with every distribution,,"

Text Editors

• Nedit editor
• gedit distributed with Gnoma Environment
• kedit editor Distributed with KDE ""Gedit"" Andk editor provide more functionality than new edit"",,

Log files

• Log flies: contain records of past system events

Removable Storage

• File systems allow you to organize your system's files
• /proc/filesystems file contains a list of autodetected filesystems

Common File Systems

• ext2 and ext3 - Most common linux file systems. Fillsystem checks can take hours
• ext2 replaced by ext3
• ext2 and ext2 sare same except jounknaling which is only present in ext 3
• EXT 4: NEW fillsystemavailble"" In Linux kernal since two thousand and eight.
• it supports large file than extended three.","

Other Storage

• XFS supports Red Hat", Is highly scalable high per force file sustem"",,
• Vfat TheV fat film systen evicted In couple forme
• Vfat .16 on M and 2,0,002.
• "Fat Disc"""" CaN Be Read By Every OperatingSystem", :"Iso 9660 Is the standard fore Mat for cordons "",,"
• UDF swap gfs reisersfs Andsoon.,",,,,

Mounting

• Mounting volumes:mount Command: Volume's

• The Mount Command",, "Makes it accessible And attaching it to a directory structure" Syntax""""#mount Type divide divide ,

• To access files on cdvrom Y must mount the cdivrom

• Mt type, divides, divide /mt/cdivrom

• devcdyrom The type divide MTCY divide .Is type device.is .thwe the system

Unmount

• The unmount Command, In foaming the system too complete any writing operation and safely detaching it:
• Unmount-medial.

Conclusion

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• Of Directing Too store fire Location off the directive and fires can be described using absolute or relative path names The 1. Textfile are the most common Filth who's contact Be viewed B Sever Utilities search that is style cat Moore andless',,,,,

Explore the Linux file system: absolute pathnames, navigating directories using commands like cd, and displaying the current working directory with pwd. Understand the role of directories and the root directory representation.